152

Practical Urology: EssEntial PrinciPlEs and PracticE

physiological effects of sodium and potassium

Absorptive Hypercalciuria

cations by showing that potassium alkali reduces

There is currently no treatment program which

urinary calcium while sodium alkali does

is capable of correcting the basic abnormality of

not.46,47 Therefore, it is advisable to generally

recommend dietary salt reduction especially

absorptivehypercalciuriaTypeI(AHI).Although

sodium cellulose phosphate had been used in

among calcium stone producers.

the past as a nonabsorbable ion exchange resin

Similarly, we recommend restriction of ani-

to bind calcium and inhibits its absorption, this

mal protein intake in stone-forming patients.

medication is no longer available.

Studies conducted under controlled clinical lab-

oratory settings have demonstrated the risk of

hypercalciuria and hyperuricosuria as a result

Thiazide

of diet high in animal protein.48-50 These find-

Thiazide is not considered a selective therapy

ings were further supported by epidemiologic

studies that found a positive correlation between

for absorptive hypercalciuria, since it does not

diets rich in protein and the high prevalence of

decrease intestinal calcium absorption in this

stone disease.51,52

condition. However, this drug has been widely

Later studies have shown the effect of dietary

used to treat absorptive hypercalciuria.

protein restriction on decreasing the levels of

Potassium supplementation should be emp-

calcium, phosphate, oxalate, and uric acid while

loyed when using thiazide therapy in order to

increasing the levels of urinary citrate.53,54

prevent hypokalemia and a decrease in urinary

citrate excretion. A typical treatment program

Restricted Oxalate Diet

might include chlorthalidone 25 mg/day with

potassium citrate 20 mEq twice/day.

Although this recommendation may be pro-

In absorptive hypercalciuria Type II, no spe-

vided to all stone patients, it is most useful for

cific drug treatment may be necessary since the

patients with enteric hyperoxaluria or underly-

physiologic defect is not as severe as in absorp-

ing bowel abnormalities.55 Traditional foods

tive hypercalciuria Type I. A low calcium intake

rich in oxalate includes: black tea, cocoa, spin-

(400–600 mg/day) and high fluid intake (suffi-

ach, mustard greens, pokeweed, swiss chard,

cient to achieve a minimum urine output of

beets,rhubarb,okra,chocolate,nuts,wheat germ,

greater than 2 L/day) would seem ideally indi-

soy crackers, pepper.

cated.

Conservative Measures

Orthophosphate

Table 11.3. (continued)

Medication

Indications

Side effects

Dose

Other notes

thiola

cystinuria

similar to

200–1,200 mg

firstline agent

penicillamine but

Po divided

less common and

bid - Qid

less severe